The spine is subject to abnormal curvature, injury, infections, tumor formation, arthritic disorders, and puncture or slippage of the cartilage disks. Modern spine surgery often involves the use of spinal implants to help stabilize the spine, correct deformities of the spine such as spondylolisthesis or pseudarthrosis, facilitate fusion, or treat spinal fractures. Some spinal implants such as a spinal fixation system may provide fused and/or rigid support for the affected regions of the spine. More recently, so called “dynamic” systems have been introduced. Dynamic spinal stabilization systems can better match a patient's anatomy than some spinal stabilization systems used to provide static support. When implanted in a patient, a dynamic spinal stabilization system can allow at least some movement (e.g., flexion, extension, lateral bending, or torsional rotation) of the affected regions of the spine in at least some of the directions, giving the patient a greater range of motion. Dynamic stabilization systems can be used in scenarios in which vertebral body fusion is not desired, in which vertebral body (re)alignment is desired, and in which it is desired to support or strengthen degraded, diseased, damaged, or otherwise weakened portions of the spine.
Often, spinal stabilization systems include rods which can bear a portion of the forces that would otherwise be transmitted along the spine. These rods may be implanted in pairs or in other numbers along portions of the spine of interest. Some spinal stabilization systems may support a portion of the spine including only two vertebrae (and associated anatomical structures) while some spinal stabilization systems support multiple levels of vertebrae. Spinal stabilizations systems can be used to support various portions of the spine, including the lumbar portion of the spine and the thoracic portion of the spine. Regardless of the number of rods implanted, or the portion of the spine in which they may be implanted, the rods can be attached to one or more vertebrae of the spine to provide support and stabilize, align, or otherwise treat the region of the spine of interest. Surgical personnel may use one or more anchor systems to attach the rods to one or more vertebrae. One such anchor system includes pedicle screws constructs which define slots, keyways, grooves, apertures, or other features for accepting and retaining stabilization rods which may be static, dynamic, or a combination of both. In many pedicle screw constructs, pedicle screws are placed in vertebrae selected by surgical personnel.
During surgical procedures, sometimes one or more rods may remain proud of its desired or final position in the rod slot of the screw head by some height or distance. Such scenarios include surgical procedures in which it is desired to anchor a rod to more than one vertebra. One such scenario can occur when pedicle screws have been implanted in two vertebrae and it is desired to anchor a rod to a third vertebra lying between the two vertebrae. In this, and other scenarios, a rod reduction instrument can be navigated to the implant site by surgical personnel to correct this situation by urging the rod into position in the pedicle screw. In some situations, the body of the rod reduction instrument may block the view of the surgical site. In other situations, the actuation handles of the instrument may rotate into the line of sight of the surgical personnel. Thus, as they attempt to reduce the rod into its desired position and lock the rod in place, surgical personnel sometimes cannot see portions of the surgical site and/or the spinal stabilization system being implanted. In some scenarios, reduced visibility of the implant site can result in slower, less efficient, and less accurate surgical results than desired. When the patient is abnormally large, the line of sight of the surgical personnel may be further impeded.
Certain surgical procedures may involve compression and/or distraction of vertebrae. For example, to treat spondylolisthesis, which is a slippage of one vertebral body on top of another, surgical personnel may need to distract the vertebrae prior to performing the reduction. To do so, surgical personnel may use a distractor or distraction instruments to hold the affected vertebrae apart or otherwise in a distracted state and then use a reduction tool or reduction instruments to perform a reduction on a slipped vertebral body and pull it back up in line with the rest of vertebrae. As another example, to place a spinal implant in a patient, surgical personnel may need to adjust the distance between the vertebrae. To do so, surgical personnel may use a compressor to bring the vertebrae closer to each other, use a distractor to pry them apart, or repeat the compression and the distraction steps, possibly swapping out one tool for another many times. For multi-level implants, adjusting the distance between the vertebrae can be a time consuming task.